1. Field of the Invention
The present invention relates to telecommunications. It relates more particularly to a multisource telecommunication antenna. The multisource antenna can be used in a system with a reflector.
2. Description of the Prior Art
Focusing systems are routinely used in space because their performance enables them to cover a plurality of terrestrial areas. However, it is not possible to produce a regular grid of contiguous coverages, which are also known as spots, with a reflector antenna associated with an array of multiple passive sources, each defining one spot access. The sources of this kind of passive focal array must meet two antagonistic constraints:
the maximum size of the sources is limited by the mesh of the focal array, and depends directly on the spacing between the spots, and
that maximum size is insufficient; the reflector being badly illuminated, the illumination yield is affected by very high spillover losses and does not meet the required specifications in terms of the required antenna gain.
It follows that a regular coverage of spots is still critical and is achieved either with a system of four reflector antennas coupled to multiple passive sources (which is the standard solution adapted for coverage in the Ka band) or with a single focal array fed reflector (FAFR) active antenna whose beam forming network (BFN) is complex.
To illuminate correctly a system 1 with a reflector 2 and a multisource array 3, it is necessary to interleave the primary sources, as shown in FIG. 1. A primary source is produced by combining a plurality of smaller sources (FAFR and associated BFN). Amplifiers must be placed between the sources and the BFN. This solution is obviously complex and costly.
Moreover, in addition to the objective of providing a multisource antenna for multispot coverage, the present invention aims to propose a compact multiband directional antenna that overcomes the overall size problems of the prior art represented by a reflector antenna with dual-band source and a system with two plane antennas.
An object of the present invention is therefore to solve the problems stated above.